Semiconductor device comprising memory semiconductor chip in which memory cell is laminated on semiconductor substrate

ABSTRACT

This semiconductor device includes a memory semiconductor chip in which a plurality of memory cells are laminated on a semiconductor substrate, a planar buffer chip which is a semiconductor chip that comprises a plurality of buffer circuits which hold data read from the memory cell and data written to the memory cell and which output the held data in accordance with the number of bit lines of the plurality of memory cells, and an electrical connection structure which electrically connects the bit lines of the memory cells of the memory semiconductor chips and the buffer circuits of the planar buffer chips to each other in a thickness direction of the memory semiconductor chip and the planar buffer chip. The electrical connection structure electrically connects the bit lines of the plurality of memory cells in the thickness direction through a penetration electrode penetrating at least the plurality of memory cells in the thickness direction.

CROSS-REFERENCE TO RELATED APPLICATION

The present application claims priority based on Japanese Patent Application No. 2020-005051 filed Jan. 16, 2020, the content of which is incorporated herein by reference.

BACKGROUND Field of the Invention

The present invention relates to a semiconductor device.

Description of Related Art

A semiconductor device such as a flash memory includes a page buffer circuit for parallel access for reading or writing of data in units of pages that are predetermined data lengths and access is allowed in units of pages (for example, refer to Japanese Unexamined Patent Application, First Publication No. 2000-100181).

SUMMARY

However, in such a semiconductor device in the related art described above, for example, a bit line of a memory cell and the page buffer circuit are connected to each other through a wiring on a flat surface of a semiconductor chip. Therefore, the data length that can be access in parallel is restricted by a wiring pitch on the flat surface. For this reason, in the semiconductor device in the related art, it is difficult to increase an access speed.

An object of an aspect of the present invention is to provide a semiconductor device capable of increasing an access speed.

An aspect of the present invention is a semiconductor device comprising: a memory semiconductor chip in which a plurality of memory cells are laminated on a semiconductor substrate; a planar buffer chip which is a semiconductor chip that comprises a plurality of buffer circuits which hold data read from the memory cell and data written to the memory cell and which output the held data in accordance with the number of bit lines of the plurality of memory cells; and an electrical connection structure which electrically connects the bit lines of the memory cells of the memory semiconductor chip and the buffer circuits of the planar buffer chip to each other in a thickness direction of the memory semiconductor chip and the planar buffer chip. The electrical connection structure electrically connects the bit lines of the plurality of memory cells in the thickness direction through a penetration electrode penetrating at least the plurality of memory cells in the thickness direction.

The foregoing semiconductor device may further include a chip laminate in which the memory semiconductor chips are laminated in the thickness direction. The memory semiconductor chips may be electrically connected to each other through the penetration electrode in the chip laminate.

The foregoing semiconductor device may further include cell strings which electrically connect the plurality of memory cells and a selection transistor to each other in the thickness direction through cell pillars, and each of the cell pillars of the plurality of cell strings disposed around the penetration electrode and the penetration electrode may be electrically connected to each other.

In the foregoing semiconductor device, the electrical connection structure may electrically connect the memory semiconductor chip and the planar buffer chip to each other through the penetration electrode penetrating the memory semiconductor chip and the planar buffer chip in the thickness direction.

In the foregoing semiconductor device, the memory cells may be NAND-type flash memory cells.

According to an aspect of the present invention, an access speed can be increased.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a configuration view showing an example of a semiconductor device according to a first embodiment.

FIG. 2 is a functional block diagram showing an example of the semiconductor device according to the first embodiment.

FIG. 3 is a cross-sectional view showing an example of a configuration of a memory cell array and a planar buffer chip according to the first embodiment.

FIG. 4 is an enlarged cross-sectional view of a portion of the memory cell array shown in FIG. 3.

FIG. 5 is a configuration view showing an electrical connection structure of the memory cell array and the planar buffer chip according to the first embodiment.

FIG. 6 is a plan view of a configuration of the electrical connection structure of the memory cell array and the planar buffer chip shown in FIG. 5.

FIG. 7 is a configuration view showing an example of connection between buffer circuits included in the planar buffer chip according to the first embodiment and sense amplifiers.

FIG. 8 is a view showing an example of a configuration of the semiconductor device in which four bit wiring layers are provided on the planar buffer chip according to the first embodiment.

FIG. 9 is a view showing an example of a configuration in which two bit wiring layers are provided on the planar buffer chip according to the first embodiment.

FIG. 10 is a configuration view showing an example of a semiconductor device according to a second embodiment.

FIG. 11 is a configuration view showing an example of a buffer decoder part according to the second embodiment.

FIG. 12 is a view of a configuration of a case in which a Y0 line of a decoder switch part is selected in the second embodiment.

FIG. 13 is a view of a configuration of a case in which an X0 line of the decoder switch part is selected in the second embodiment.

FIG. 14 is a cross-sectional view showing another example of a configuration of the semiconductor device.

FIG. 15 is a cross-sectional view showing another example of a configuration of the semiconductor device.

FIG. 16 is a cross-sectional view showing another example of a configuration of the semiconductor device.

DESCRIPTION OF THE EMBODIMENTS

Hereinafter, a semiconductor device according to embodiments of the present invention will be described with reference to the drawings.

First Embodiment

FIG. 1 is a configuration view showing an example of a semiconductor device 1 according to a first embodiment.

As shown in FIG. 1, the semiconductor device 1 is, for example, a three-dimensional (3D) NAND-type flash memory device and includes a memory semiconductor chip 10, a planar buffer chip 20, and TSV (Through-Silicon Via) 30.

The memory semiconductor chip 10 is a semiconductor chip provided with a memory cell array 40 including a plurality of memory cells (NAND-type flash memory cells) MC. A detailed configuration of the memory cell array 40 will be described below.

The planar buffer chip 20 is a semiconductor chip provided with a plurality of buffer circuits 21 in accordance with the number of bit lines (reading lines) of the memory semiconductor chip 10. The buffer circuit 21 is a circuit holding data read from the memory cell MC and data written in the memory cell MC. The buffer circuit 21 outputs held data as readout data at the time of reading. The buffer circuit 21 outputs held data as write data to the memory cell MC at the time of writing.

The TSV 30 is a bumpless penetration electrode penetrating the memory semiconductor chip 10 and the planar buffer chip 20 in a thickness direction and that connects the memory semiconductor chip 10 to the planar buffer chip 20 using a conductor. The TSV 30 electrically connects the bit line of the memory cell MC and the buffer circuit 21 to each other in the thickness direction of the memory semiconductor chip 10 and the planar buffer chip 20.

FIG. 2 is a functional block diagram showing an example of the semiconductor device 1 according to the present embodiment. As shown in FIG. 2, the semiconductor device 1 includes an address decoder 11, a voltage generation circuit 12, a control circuit 13, a planar buffer part 200, and the memory cell array 40.

The address decoder 11 decodes input address information and outputs a control signal for selecting a memory cell MC of the memory cell array 40.

The voltage generation circuit 12 generates an erase voltage necessary for erasing data and a write voltage necessary for writing data and supplies the generated erase voltage and write voltage to the memory cell array 40 that is a flash memory.

The control circuit 13 is a logic circuit for controlling the semiconductor device 1 in response to an input from outside. The control circuit 13 controls, for example, reading data from the memory cell array 40, erasing data of the memory cell array 40, and writing data to the memory cell array 40.

In order to collectively read or write data of a predetermined data length (bit width), the planar buffer part 200 includes the buffer circuits 21 in accordance with the predetermined data length (bit width). In the present embodiment, data having a predetermined data length (bit width) is defined as “a page”, and the planar buffer part 200 retains page data.

The buffer circuit 21 according to the present embodiment is connected to the bit line of the memory cell array 40 that is drawn out in the thickness direction through the TSV 30, and a plurality of buffer circuits 21 are arranged two-dimensionally on a planar shape on a plane of the planar buffer chip 20.

Next, with reference to FIGS. 3 to 6, a configuration of the memory cell array 40 according to the present embodiment will be described.

FIG. 3 is a cross-sectional view showing an example of a configuration of the memory cell array 40 and the planar buffer chip 20. FIG. 4 is an enlarged cross-sectional view of a portion of the memory cell array 40 shown in FIG. 3. FIG. 5 is a configuration view showing an electrical connection structure of the memory cell array 40 and the planar buffer chip 20. FIG. 6 is a plan view of a configuration of the electrical connection structure of the memory cell array 40 and the planar buffer chip 20 shown in FIG. 5.

As shown in FIGS. 3 to 6, the memory cell array 40 includes a plurality of gate plate electrodes (10-SGS, 10-0, (ellipsis), 10-30, 10-31, and 10-SGD) laminated in the thickness direction (Z axis direction) of the memory semiconductor chip 10.

In addition, the memory cell array 40 includes a plurality of NAND cell strings NS in which the plurality of memory cells MC and selection transistors (TR1 and TR2) are connected in series. The plurality of NAND cell strings (NAND strings) NS are disposed in a matrix shape within a surface of the memory semiconductor chip 10.

In the NAND cell strings NS, for example, a grounding selection transistor TR1, 32 memory cells MC, and the data selection transistor TR2 are connected in series between a bit lines and a ground (GND) line.

The 32 memory cells MC are connected in series between the grounding selection transistor TR1 and the data selection transistor TR2. Cell gate signal lines (CGO to CG31) are connected to each gate terminals, and the 32 memory cells MC are controlled in accordance with any signal of a CGO signal to a CG31 signal.

The grounding selection transistor TR1 is an N-type metal-oxide-semiconductor field-effect transistor (NMOS transistor (N-type MOSFET)) disposed between the 32 memory cells MC and the GND line. An SGS signal line is connected to the gate terminal of the grounding selection transistor TR1, and the grounding selection transistor TR1 is controlled by SGS signals.

The data selection transistor TR2 is an NMOS transistor disposed between the bit lines and the 32 memory cells MC. Any of signal lines SGDx0, SGDx1, SGDy0, and SGDy1 is connected to the gate terminals of the data selection transistor TR2, and the data selection transistor TR2 is controlled by any signal of an SGDx0 signal, an SGDx1 signal, an SGDy0 signal, and an SGDy1 signal.

The SGDx0 signal, the SGDx1 signal, the SGDy0 signal, the SGDy1 signal, the SGS signal, and the CGO signal to the CG31 signal are generated by the address decoder 11 and the control circuit 13 described above.

Each connection between the grounding selection transistor TR1, the 32 memory cells MC, and the data selection transistor TR2 is made in a thick direction (Z-axis direction) so as to penetrate through the plurality of gate plate electrodes (10-SGS, 10-0, (ellipsis), 10-30, 10-31, and 10-SGD) by cell pillars (penetration electrodes) CP which are penetration electrodes.

Next, with reference to the drawings, operation of the semiconductor device 1 according to the present embodiment will be described.

In FIG. 2 described above, in reading out data is from the semiconductor device 1, for example, a data readout command are input to the semiconductor device 1, first, the address decoder 11 generates the SGDx0 signal, the SGDx1 signal, the SGDy0 signal, the SGDy1 signal, the SGS signal, and the CGO to CG31 signals for selecting a memory cell MC to be read out on the basis of the input address information.

Specifically, the address decoder 11 selects the NAND cell strings NS by setting any of the SGDx0 signal and the SGDx1 signal and any of the SGDy0 signal and the SGDy1 signal to a high state and setting other signals to a low state. In addition, the address decoder 11 selects one memory cell MC of the selected NAND cell strings NS by setting any one of the CGO to CG31 signals to a low state and setting other signals to a high state.

From the selected memory cell MC, “0” or “1” can be read out depending on whether or not a current flows in an OFF state in which the gate terminal is in the low state. The data of “0” or “1” held by the memory cell MC is input to the buffer circuit 21 through the bit lines and the TSV 30 and is held by the buffer circuit 21. Here, data of a predetermined data length (bit width) is read out in parallel from the memory cell array 40 and retained in the planar buffer part 200.

In response to the data readout command, the control circuit 13 allows the planar buffer part 200 to hold readout data sequentially output held readout data to the outside.

In writing data in the semiconductor device 1, when address information, for example, a data writing command, and write data are input to the semiconductor device 1, the control circuit 13 allows the planar buffer part 200 to hold the write data. Then, the address decoder 11 generates the SGDx0 signal, the SGDx1 signal, the SGDy0 signal, the SGDy1 signal, the SGS signal, and the CGO to CG31 signals for selecting a memory cell MC to be read on the basis of the input address information, and the control circuit 13 writes data of a predetermined data length (bit width) in parallel by applying a writing voltage to the memory cell array 40 from the voltage generation circuit 12.

Next, with reference to FIGS. 3 to 6, the electrical connection structure of a chip laminate 10A, in which a plurality of memory semiconductor chips 10 according to the present embodiment are laminated in the thickness direction, and the planar buffer chips 20 will be described.

As shown in FIGS. 3, 4, and 5, the semiconductor device 1 of the present embodiment has electrical connection structures in which the bit lines of the memory cells MC of the memory semiconductor chips 10 described above and the buffer circuit 21 of the planar buffer chips 20 are electrically connected to each other through the TSV 30 penetrating the memory semiconductor chips 10 and the planar buffer chip 20 in the thickness direction.

In addition, the semiconductor device 1 of the present embodiment includes the chip laminate 10A in which the plurality of memory semiconductor chips 10 having the plurality of memory cells MC laminated on a semiconductor substrate SB are laminated in the thickness direction.

The semiconductor substrate SB is provided with, for example, a decoder, a string driver, and the like. The plurality of memory cells MC are laminated on this semiconductor substrate SB and constitute the memory cell array 40 described above.

FIGS. 3 and 4 illustrate a state in which the plurality of memory semiconductor chips 10 and the planar buffer chips 20 are separated from each other. However, actually, the plurality of memory semiconductor chips 10 and the planar buffer chips 20 are in a state of being directly adhered to each other or in a state of being adhered to each other with an intermediate layer (adhesive layer or the like) interposed therebetween.

The chip laminate 10A has a bumpless structure in which the plurality of memory semiconductor chips 10 are electrically connected to each other through the TSV 30 without having a bump electrode disposed between the plurality of memory semiconductor chips 10.

In addition, each of the memory semiconductor chips 10 has a structure in which the bit lines of the plurality of memory cells MC are electrically connected in the thickness direction through the TSV 30. Among these, in the memory semiconductor chip 10 positioned in the lowermost layer, the TSV 30 is provided in a state of penetrating the plurality of memory cells MC in the thickness direction. On the other hand, in the remaining memory semiconductor chips 10 positioned in layers above this lowermost layer, the TSV 30 is provided in a state of penetrating the plurality of memory cells MC and the semiconductor substrate SB in the thickness direction.

As shown in FIGS. 3 to 6, the chip laminate 10A has a structure in which each of the cell pillars CP of the plurality of NAND cell strings NS disposed around the TSV 30 and the TSV 30 are electrically connected to each other through bit wiring layers 31 and contact plugs 32. That is, the plurality of NAND cell strings NS are disposed so as to surround TSV 30 in a plan view and is connected to the TSV 30 in parallel through the bit wiring layers 31 and the contact plugs 32.

The bit wiring layers 31 are, for example, part of the bit lines of the semiconductor chips10. The bit wiring layers 31 are provided within interlayer insulating layers 33 laminated on the respective memory semiconductor chips 10 and electrically connected to the TSVs 30. The contact plug 32 electrically connects the bit wiring layer 31 and the cell pillar CP to each other in a state of penetrating the interlayer insulating layer 33 in the thickness direction. The bit wiring layer 31 may be directly connected to the cell pillar CP extending in the thickness direction without passing through the contact plug 32.

Next, with reference to FIGS. 7 to 9, a configuration of the planar buffer chip 20 according to the present embodiment will be described.

FIG. 7 is a configuration view showing an example of connection between the buffer circuits 21 included in the planar buffer chip 20 and sense amplifiers 60 according to the present embodiment.

As shown in FIG. 7, the plurality of buffer circuits 21 included in the planar buffer chip 20 are electrically connected to the sense amplifiers 60 through a plurality of bit wiring layers 22 (22_BL0, 22_/BL0, 22_BL1, 22_/BL1, 22_BL2, 22_/BL2, 22_BL3, and 22_/BL3) provided for each pair of respective bit lines of the respective buffer circuits 21. The sense amplifiers 60 are provided in accordance with the respective buffer circuits 21 and detect and amplify data output from each of the buffer circuits 21. In FIG. 7, the semiconductor device 1 comprising four bit wiring layers 22 is shown as an example.

In addition, FIG. 8 is a view showing an example of a configuration of the semiconductor device 1 in which four bit wiring layers 22 are provided on the planar buffer chip 20 according to the present embodiment.

As shown in FIG. 8, the buffer circuit 21 according to the present embodiment is connected so as to form the bit lines of the memory cell array 40 drawn out in the thickness direction through the TSV 30, and a plurality of buffer circuits 21 are arranged two-dimensionally on a plane of the planar buffer chip 20.

On the planar buffer chip 20, the bit wiring layers 22 provided for each pair of respective bit lines of the buffer circuits 21 are laminated and disposed through interlayer insulating layers 23. In addition, a pair of respective bit lines of the buffer circuits 21 and the bit wiring layers 22 corresponding to the respective buffer circuits 21 are electrically connected to each other through contact plugs 24 penetrating the interlayer insulating layers 23 in the thickness direction. In FIG. 8, the interlayer insulating layers 23 are shown as spaces.

FIG. 8 shows an example of a configuration in which four bit wiring layers 22 (22_BL0, 22_/BL0, 22_BL1, 22_/BL1, 22_BL2, 22_/BL2, 22_BL3, and 22_/BL3) are laminated and disposed on the planar buffer chip 20 with respect to the four buffer circuits 21 (which will hereinafter be distinguished as buffer circuits 21A, 21B, 21C, and 21D).

That is, the pair of bit wiring layers 22_BL0 and 22_/BL0 in the lowermost layer (first layer) and a pair of bit lines of the buffer circuit 21A are electrically connected to each other through the pair of contact plugs 24 penetrating the interlayer insulating layers 23 in the thickness direction.

In addition, the pair of bit wiring layers 22_BL1 and 22_/BL1 in a second layer and a pair of bit lines of the buffer circuit 21B are electrically connected to each other through the pair of contact plugs 24 penetrating the interlayer insulating layers 23 in the thickness direction.

In addition, the pair of bit wiring layers 22_BL2 and 22_/BL2 in a third layer and a pair of bit lines of the buffer circuit 21C are electrically connected to each other through the pair of contact plugs 24 penetrating the interlayer insulating layers 23 in the thickness direction.

In addition, the pair of bit wiring layers 22_BL3 and 22_/BL3 in the uppermost layer (fourth layer) and a pair of bit lines of the buffer circuit 21D are electrically connected to each other through the pair of contact plugs 24 penetrating the interlayer insulating layers 23 in the thickness direction.

FIG. 9 is a view showing an example of a configuration in which two bit wiring layers 22 are provided on the planar buffer chip 20 according to the present embodiment. In FIG. 9, the interlayer insulating layers 23 are shown as spaces.

FIG. 9 shows an example of a configuration in which two bit wiring layers 22 (22_BL00, 22_/BL00, 22_BL01, 22_/BL01, 22_BL10, 22_/BL10, 22_BL11, and 22_/BL11) are laminated and disposed on the planar buffer chip 20 with respect to the four buffer circuits 21 (21A, 21B, 21C, and 21D).

That is, the pair of bit wiring layers 22_BL00 and 22_/BL00 in the lowermost layer (first layer) and the pair of bit lines of the buffer circuit 21A are electrically connected to each other through the pair of contact plugs 24 penetrating the interlayer insulating layers 23 in the thickness direction.

In addition, the pair of bit wiring layers 22_BL01 and 22_/BL01 which are positioned in the same layer (first layer) as the pair of bit wiring layers 22_BL00 and 22_/BL00 and the pair of bit lines of the buffer circuit 21C are electrically connected to each other through the pair of contact plugs 24 penetrating the interlayer insulating layers 23 in the thickness direction.

In addition, the pair of bit wiring layers 22_BL10 and 22_/BL10 in the uppermost layer (second layer) and the pair of bit lines of the buffer circuit 21B are electrically connected to each other through the pair of contact plugs 24 penetrating the interlayer insulating layers 23 in the thickness direction.

In addition, the pair of bit wiring layers 22_BL11 and 22_/BL11 positioned in the same layer (second layer) as the pair of bit wiring layers 22_BL10 and 22_/BL10 and the pair of bit lines of the buffer circuit 21D are electrically connected to each other through the pair of contact plugs 24 penetrating the interlayer insulating layers 23 in the thickness direction.

In the semiconductor device 1 of the present embodiment, data can be accessed in (be read and written in) the plurality of buffer circuits 21 of the planar buffer chip 20 through the plurality of bit wiring layers 22 at the same time. Therefore, in the semiconductor device 1 according to the present embodiment, an access speed can be increased.

In addition, in the semiconductor device 1 of the present embodiment, there is no need to extremely minify design rules with respect to respective bit wiring layers 22 by laminating and disposing a plurality of bit wiring layers 22 on the planar buffer chip 20.

The present embodiment is not limited to a configuration in which two or four bit wiring layers 22 are disposed as described above, and the number of laminated bit wiring layers 22 can be suitably changed. For example, a configuration in which eight bit wiring layers 22 are disposed on the planar buffer chip 20 can be adopted. In addition, the number of bit wiring layers 22 disposed in each layer can also be suitably changed in accordance with the number of plurality of buffer circuits 21 disposed on the planar buffer chip 20.

As described above, the semiconductor device 1 according to the present embodiment includes the memory semiconductor chip 10 and the TSVs 30 (electrical connection structure). The memory semiconductor chip 10 includes the plurality of memory cells MC. The planar buffer chip 20 is the semiconductor chip that comprises a plurality of the buffer circuits in accordance with the number of the memory cells MC. The buffer circuits 21 are circuits that hold data read from the memory cells MC and data written in the memory cells MC. The TSV 30 electrically connects the bit lines of the memory cells MC of the memory semiconductor chip 10 and the buffer circuit 21 of the planar buffer chip 20 to each other in the thickness direction of the memory semiconductor chip 10 and the planar buffer chip 20. In addition, the plurality of bit wiring layers 22 electrically connected to the respective bit lines of the buffer circuits 21 are laminated and disposed on the planar buffer chip 20.

Accordingly, in the semiconductor device 1 according to the present embodiment, since the buffer circuits 21 can be arranged on the planar buffer chip 20 in a two-dimensional planar shape (for example, an XY plane shape), it is possible to have parallel access (reading and writing) to more memory cells MC. Hence, in the semiconductor device 1 according to the present embodiment, the access speed can be increased.

Conventionally, for example, one-dimensional line access has been provided in a technology in the related art, but in the semiconductor device 1 according to the present embodiment, by having two-dimensional surface access, the access speed can be improved by one digit or two digits. For example, in the technology in the related art, since 16 kilobytes (KB) for one page are written in 1 millisecond (ms), a throughput thereof is 16 MB/s. In contrast, in the semiconductor device 1 according to the present embodiment, for example, parallel processing for ten pages (160 KB) can be performed, and thus the speed of throughput can be increased to 160 MB/s.

In addition, in the semiconductor device 1 according to the present embodiment, the bit lines of the memory cells MC and the buffer circuits 21 of the planar buffer chips 20 are electrically connected to each other in the thickness direction (Z axis direction) in a three-dimensional manner. Therefore, for example, as in the technology in the related art, there is no need to have connection through the wirings on the flat surfaces of the semiconductor chips, and routing of the wirings is not restricted by a wiring pitch on the flat surface. Thus, in the semiconductor device 1 according to the present embodiment, the chip sizes of the memory semiconductor chips 10 can be reduced.

In addition, in the present embodiment, the plurality of gate plate electrodes (10-SGS, 10-0, (ellipsis), 10-30, 10-31, and 10-SGD) including the memory cells MC are laminated in the thickness direction in the memory semiconductor chips 10. The TSV 30 electrically connects the plurality of laminated gate plate electrodes (10-SGS, 10-0, (ellipsis), 10-30, 10-31, and 10-SGD) and the planar buffer chip 20 to each other.

Accordingly, the semiconductor device 1 according to the present embodiment has a memory semiconductor chip 10 (memory cell arrays 40) defined in a three-dimensional manner. Therefore, the chip size of the memory semiconductor chip 10 can be further reduced, and the access speed can be further increased.

In addition, in the present embodiment, the TSV 30 is a penetration electrode penetrating the memory semiconductor chip 10 and the planar buffer chip 20 in the thickness direction and connecting the memory semiconductor chip 10 and the planar buffer chip 20 through a conductor. That is, the TSV 30 is a bumpless penetration electrode.

Accordingly, in the semiconductor device 1 according to the present embodiment, for example, compared to a case of using bumps in the technology in the related art, the pitch of the TSVs 30 can be extremely reduced, and more buffer circuits 21 can be disposed in the planar buffer chips 20. Thus, in the semiconductor device 1 according to the present embodiment, the chip sizes can be further reduced, and the access speed can be further increased.

In addition, compared to bumps in the technology in the related art, since the TSV 30 allows the semiconductor chip to be thinned, an impedance of connection can be reduced. For this reason, in the semiconductor device 1 according to the present embodiment, noise can be reduced and the access speed can be further increased.

In addition, the semiconductor device 1 according to the present embodiment has an electrical connection structure in which the bit lines of the plurality of memory cells MC are electrically connected in the thickness direction through the TSV 30 penetrating at least the plurality of memory cells MC in the thickness direction.

Accordingly, even when the number of plurality of memory cells MC electrically connected in the thickness direction is increased for each of the NAND cell strings NS of the memory semiconductor chips 10, reliability of electrical connection between the plurality of memory cells MC can be ensured.

Moreover, the semiconductor device 1 according to the present embodiment has an electrical connection structure in which the memory semiconductor chips 10 are electrically connected to each other through the TSV 30 in the chip laminate 10A in which the plurality of memory semiconductor chips 10 having the plurality of memory cells MC laminated on the semiconductor substrate SB are laminated in the thickness direction.

Accordingly, the number of plurality of memory cells MC electrically connected in the thickness direction of the chip laminate 10A can be increased. In addition, even when there is restriction (limitation) on the number of plurality of memory cells MC electrically connected in the thickness direction for each of the NAND cell strings NS of the memory semiconductor chips 10, reliability of electrical connection between the plurality of memory cells MC laminated in the thickness direction can be ensured for each of the NAND cell strings NS of the memory semiconductor chips 10.

Incidentally, for example, in a deep hole processing step of a 3D NAND flash memory device, there is limitation on an aspect ratio (a depth of a hole to a diameter of the hole) of a deep hole, and the number of laminated gate plate electrodes which can be penetrated at one time is 64 layers. For this reason, when the number of laminated gate plate electrodes is 128 layers, there is a need to repeat a lamination step for laminating 64 layers of the gate plate electrodes and a deep hole step twice. Moreover, when the number of laminated gate plate electrodes is 256 layers, there is a need to repeat the lamination step for laminating 64 layers of the gate plate electrodes and the deep hole step four times.

In addition, in the lamination step for laminating 64 layers of the gate plate electrodes, a heating step is added in processing of forming a tunnel oxide film or the like. Therefore, diffusion of source/drain of a transistor constituting a peripheral micro-circuit progresses due to the influence of heat. As a result, not only the transistor characteristics become dull but also there is a need to lengthen the distance of the source/drain. Therefore, it is difficult to produce a high-performance micro-transistor.

Moreover, regarding the influence of such a heating step on transistors of peripheral circuits, they come under an equivalent influence when peripheral circuits are disposed next to a memory array in a CMOS Next Array (CNA) or when peripheral circuits are disposed immediately below a memory array in a CMOS Under Array (CUA).

On the other hand, when the number of plurality of memory cells electrically connected in the thickness direction is increased, a reading current of the memory cells significantly decreases as the resistance increases due to series connection of the memory cells, and a speed of random page access is reduced. As a result, this causes a problem that it takes time for cueing of data reading. In this case, since the number of memory cells in series connection becomes twice or four times from an application side, a size of an erasing block also becomes twice or four times.

Moreover, in a NAND flash memory, when new data is rewritten (overwritten), in order to protect data which has already been written and is not to be changed, there is a need to copy (moving work) data to a block which has already been erased. In this case as well, the number of memory cells in series connection becomes twice or four times, and thus moving work of data becomes twice or four times.

In order to avoid these problems, a method in which bit lines and source lines are interposed at certain intervals between gate plate electrodes laminated in the thickness direction can be considered. For example, while having 64 layers or 128 layers in one NAND memory cell series (NAND string unit), bit lines and source lines are provided in each NAND memory cell series. However, in this case as well, a new problem occurs. This is because different bit lines are consequently laminated in a perpendicular direction (thickness direction) in a planar layout of a memory cell array, and thus it is difficult to arrange the layout thereof.

In contrast, in the semiconductor device 1 according to the present embodiment, such a problem can be resolved by employing an electrical connection structure using the TSV 30 described above. That is, a plurality of memory semiconductor chips 10 having 64 layers of the gate plate electrodes are produced, and the chip laminate 10A in which the plurality of memory semiconductor chips 10 are laminated in the thickness direction is produced. Thereafter, the TSV 30 penetrating the plurality of memory semiconductor chips 10 in the thickness direction are formed.

Accordingly, in one memory semiconductor chip, there is no need to repeat the lamination step for laminating 64 layers of the gate plate electrodes and the deep hole step described above, and thus the influence of heat on transistors of peripheral circuits due to the heating step can also be avoided. In addition, since increase in resistance due to series connection of the plurality of memory cells MC can also be curbed using the TSV 30 penetrating the chip laminate 10A in the thickness direction, it is also possible to avoid reduction of the speed of random page access or delay of moving work of data. Moreover, the number of memory cells MC electrically connected to the thickness direction can be increased.

In addition, the semiconductor device 1 according to the present embodiment has an electrical connection structure in which each of the cell pillars CP of the plurality of NAND cell strings NS disposed around the TSV 30 and the TSV 30 are electrically connected to each other.

Accordingly, a capacity thereof can be further increased by increasing the number of NAND cell strings NS connected in parallel through the TSV 30.

Incidentally, signal lines SGy0 and SGy1 are orthogonal to other signal lines SGx0 and SGx1 or the gate plate electrodes (10-SGS, 10-0, (ellipsis), 10-30, 10-31, and 10-SGD). The signal lines SGx0 and SGx1 or the gate plate electrodes (10-SGS, 10-0, (ellipsis), 10-30, 10-31, and 10-SGD) are produced in a damascene process in which a dummy layer of SiN is removed and is replaced with tungsten (W). On the other hand, the signal lines SGy0 and SGy1 are produced by performing processing of reactive ion etching (RIE) after depositing tungsten (W).

The thickness of deposited tungsten (W) can be adjusted during a process. For example, compared to the thickness of 20 nm of the signal lines SGx0 and SGx1 or the gate plate electrodes (10-SGS, 10-0, (ellipsis), 10-30, 10-31, and 10-SGD) in a different damascene process, a withstand voltage is raised by setting the thickness to 130 nm which is thick. Accordingly, since a high voltage is applied to the NAND cell strings NS at the time of rewriting, a punch-through phenomenon is prevented from occurring on a side in contact with the bit lines.

In addition, at the time of writing, write inhibition NAND cell strings NS are boosted to approximately 10 V. For this reason, the signal lines SGy0 and SGy1 are completely cut off in order to prevent leakage of an electric charge from flowing from the NAND cell strings NS to the bit lines side and prevent a writing error from occurring.

On the other hand, at the time of erasing, the NAND cell strings NS are boosted to approximately 20 V. At this time, the signal lines SGy0 and SGy1 play a role as buffer transistors for preventing a punch-through from occurring on the bit lines side.

In addition, circuits such as a high-withstand voltage string driver, a row decoder, and the like are produced on the semiconductor substrate SB. These make an embodiment of the present invention effective in both cases in a CUA which is provided immediately below the memory cell array 40 and in a CAN which is not provided immediately below the same.

In addition, in the semiconductor substrate SB, bulk erasing of applying 20 V to the semiconductor substrate SB at the time of erasing using p-type silicon in which single crystal and a bottom part of the NAND cell strings NS are subjected to epitaxial growth may be used. In addition, a CUA may be provided immediately below the NAND cell strings NS, and the NAND cell strings NS may be produced on a polysilicon substrate.

In this case, gate induced drain leakage (GIDL) erasing may be used. In GIDL erasing, when the NAND cell strings NS are boosted at the time of erasing, a source voltage of the NAND cell strings NS is raised higher by several V than a voltage of a selection gate on the source side of the NAND cell strings NS and gradually boosted to approximately 20 V. Therefore, a GIDL current is generated, and the NAND cell strings NS are boosted to 20 V necessary for erasing.

Second Embodiment

Next, with reference to the drawings, a semiconductor device 1 a according to a second embodiment will be described.

FIG. 10 is a configuration view showing an example of the semiconductor device 1 a according to the second embodiment.

As shown in FIG. 10, the semiconductor device 1 a is NAND-type flash memory device, for example, and includes the memory semiconductor chip 10, a decoder 10B, the planar buffer chip 20, and the TSV 30. In FIG. 10, the same reference signs are applied to the same constituents as those in FIG. 1 described above, and description thereof will be omitted.

The decoder 10B includes a buffer decoder part 50 for selecting one buffer circuit 21 from bit lines of a predetermined number of memory cells. In the present embodiment, the memory semiconductor chip 10 and the planar buffer chip 20 are connected to each other through the TSV 30 via the decoder 10B. The decoder 10B is disposed inside the memory semiconductor chip 10.

Next, with reference to FIGS. 11 to 13, a configuration of the buffer decoder part 50 will be described. FIG. 11 is a configuration view showing an example of the buffer decoder part 50 according to the present embodiment. As shown in FIG. 11, the buffer decoder part 50 includes an X buffer decoder 51, a Y buffer decoder 52, and a decoder switch part 53.

The X buffer decoder 51 generates selection signals X0 to X7 by decoding three bits of address information.

The Y buffer decoder 52 generates selection signals Y0 to Y7 by decoding three bits of address information different from the address information of the X buffer decoder 51.

The decoder switch part 53 selects one of 64 bit lines and connects it to the buffer circuits 21 using a combination of the selection signals X0 to X7 generated by the X buffer decoder 51 and the selection signals Y0 to Y7 generated by the Y buffer decoder 52.

In the present embodiment, one buffer circuit 21 is connected to one decoder switch part 53 through the TSV 30. In addition, one NAND cell string NS is connected to each of the 64 bit lines.

Next, with reference to FIGS. 12 and 13, a configuration of the decoder switch part 53 will be described.

FIG. 12 is a view of a configuration of a case in which a Y0 line of the decoder switch part 53 according to the present embodiment is selected. In addition, FIG. 13 is a view of a configuration of a case in which an X0 line of the decoder switch part 53 according to the present embodiment is selected.

As shown in FIGS. 12 and 13, the decoder switch part 53 includes a selection switch part SW1 and a selection switch part SW2.

The selection switch part SW1 is a selection switch controlled in accordance with the selection signals X0 to X7 generated by the X buffer decoder 51. In addition, the selection switch part SW2 is a selection switch controlled in accordance with the selection signals Y0 to Y7 generated by the Y buffer decoder 52.

The decoder switch part 53 selects one of the 64 NAND cell strings NS using a matrix of the selection switch part SW1 and the selection switch part SW2 and connects it to the buffer circuit 21 through the TSV 30.

The decoder switch part 53 and each of the NAND cell strings NS are electrically connected to each other using polysilicon or the like similar to that inside the NAND cell strings NS. In addition, the selection switch part SW1 and the selection switch part SW2 are disposed on the decoder 10B.

As described above, the semiconductor device 1 a according to the present embodiment includes the memory semiconductor chip 10, the planar buffer chip 20, and the TSV 30 (electrical connection structure) described above and also includes the buffer decoder part 50. The buffer decoder part 50 selects one of a predetermined number (for example, 64) of bit lines of the memory cell and connects it to the buffer circuit 21.

Accordingly, the semiconductor device 1 a according to the present embodiment can select one from the appropriate number of bit lines and connect the selected one bit line to the buffer circuit 21.

In the semiconductor device 1 a according to the present embodiment, although illustration is omitted, similar to the foregoing semiconductor device 1, an electrical connection structure using the TSV 30 described above can be employed. In addition, similar to the foregoing semiconductor device 1, the plurality of bit wiring layers 22 electrically connected to the respective bit lines of the buffer circuits 21 can be laminated and disposed on the planar buffer chip 20.

The present invention is not limited to each of the foregoing embodiments and can be changed within a range not departing from the gist of the present invention.

For example, the foregoing semiconductor device 1 can have configurations as shown in FIGS. 14 to 16.

Specifically, in the semiconductor device 1 shown in FIG. 14, the chip laminate 10A having the plurality of memory semiconductor chips 10 laminated in the thickness direction has a configuration in which the TSV 30 is electrically connected to the plurality of NAND cell strings NS of the memory semiconductor chip 10 positioned in the lowermost layer through the bit wiring layers 31 and the contact plugs 32 without penetrating the plurality of memory cells MC of the memory semiconductor chip 10 positioned in the lowermost layer in the thickness direction.

On the other hand, the semiconductor device 1 shown in FIG. 15 has a configuration in which the planar buffer chip 20 is disposed below the chip laminate 10A having the plurality of memory semiconductor chips 10 laminated in the thickness direction and the plurality of memory semiconductor chips 10 and the planar buffer chip 20 are electrically connected to each other through the TSV 30 penetrating these in the thickness direction.

On the other hand, the semiconductor device 1 shown in FIG. 16 has a configuration in which the memory cell array 40 constituted of the chip laminate 10A shown in FIG. 15 and the control circuit 13 controlling this memory cell array 40 are mounted on an interposer IP and the memory cell array 40 and the control circuit 13 are electrically connected to each other through this interposer IP.

In each of the foregoing embodiments, an example in which the memory semiconductor chip 10 and the planar buffer chip 20 are connected to each other through the TSV 30 has been described. However, the present invention is not limited thereto, and they may be connected to each other using a different electrical connection structure such as a bump.

In addition, in each of the foregoing embodiments, an example in which the semiconductor device 1 (1 a) is a flash memory device has been described. However, the present invention is not limited thereto, and it may be applied to other semiconductor memories.

In addition, in each of the foregoing embodiments, an example in which the planar buffer chip 20 is disposed on a side above the memory semiconductor chip 10 has been described. However, the present invention is not limited thereto, and it may be disposed on a side below the memory semiconductor chip 10 or the memory semiconductor chip 10 may be disposed above and below the planar buffer chip 20.

In addition, in the foregoing second embodiment, an example in which the buffer decoder part 50 is disposed in another decoder 10B different from the planar buffer chip 20 has been described. However, it may be disposed on the planar buffer chip 20 together with the buffer circuit 21.

In addition, without providing the buffer decoder part 50, for example, one buffer circuit 21 may be connected to one NAND cell string NS through the TSV 30. While preferred embodiments of the invention have been described and shown above, it should be understood that these are exemplary of the invention and are not to be considered as limiting. Additions, omissions, substitutions, and other modifications can be made without departing from the spirit or scope of the present invention. Accordingly, the invention is not to be considered as being limited by the foregoing description, and is only limited by the scope of the appended claims.

EXPLANATION OF REFERENCES

-   -   1, 1 a Semiconductor device     -   10 Memory semiconductor chip     -   10A Chip laminate     -   10-SGS, 10-0, 10-30, 10-31, 10-SGD Gate plate electrode     -   10B Decoder     -   11 Address decoder     -   12 Voltage generation circuit     -   13 Control circuit     -   20 Planar buffer chip     -   21 Buffer circuit     -   22 Bit wiring layer     -   23 Interlayer insulating layer     -   24 Contact plug     -   30 TSV (penetration electrode)     -   31 Bit wiring layer     -   32 Contact plug     -   33 Interlayer insulating layer     -   40 Memory cell array     -   50 Buffer decoder part     -   51 X buffer decoder     -   52 Y buffer decoder     -   53 Decoder switch part     -   60 Sense amplifier     -   200 Planar buffer part     -   CP Cell pillar     -   MC Memory cell     -   NS NAND cell string     -   SW1, SW2 Selection switch part     -   TR1, TR2 Selection transistor 

What is claimed is:
 1. A semiconductor device comprising: a memory semiconductor chip in which a plurality of memory cells are laminated on a semiconductor substrate; a planar buffer chip which is a semiconductor chip that comprises a plurality of buffer circuits which hold data read from the memory cell and data written to the memory cell and which output the held data in accordance with the number of bit lines of the plurality of memory cells; and an electrical connection structure which electrically connects the bit lines of the memory cells of the memory semiconductor chip and the buffer circuits of the planar buffer chips to each other in a thickness direction of the memory semiconductor chip and the planar buffer chip, wherein the electrical connection structure electrically connects the bit lines of the plurality of memory cells in the thickness direction through a penetration electrode penetrating at least the plurality of memory cells in the thickness direction.
 2. The semiconductor device according to claim 1 further comprising: a chip laminate in which the memory semiconductor chips are laminated in the thickness direction, wherein the memory semiconductor chips are electrically connected to each other through the penetration electrode in the chip laminate.
 3. The semiconductor device according to claim 1 further comprising: cell strings which electrically connect the plurality of memory cells and a selection transistor to each other in the thickness direction through cell pillars, wherein each of the cell pillars of the plurality of cell strings disposed around the penetration electrode and the penetration electrode are electrically connected to each other.
 4. The semiconductor device according to claim 1, wherein the electrical connection structure electrically connects the memory semiconductor chip and the planar buffer chip to each other through the penetration electrode penetrating the memory semiconductor chip and the planar buffer chip in the thickness direction.
 5. The semiconductor device according to claim 1, the memory cells are NAND-type flash memory cells. 